/**
 * @param {string} current
 * @param {string} correct
 * @return {number}
 */
 var convertTime = function(current, correct) {
  const parse = time => {
    const arr = time.split(':').map(v => +v)
    return arr[0] * 60 + arr[1]
  }
  let a = parse(current), b = parse(correct)
  let diff = b - a
  let ans = 0
  let x = Math.floor(diff/60)
  ans += x
  diff -= 60 * x
  x = Math.floor(diff/15)
  ans += x
  diff -= 15 * x
  x = Math.floor(diff/5)
  ans += x
  diff -= 5 * x
  ans += diff
  return ans
};